London: At least 22 people were injured after a bomb detonated on a packed London Underground train on Friday, setting off a "wall of fire" that burned commuters in Britain's fifth terror attack in six months.
Witnesses saw passengers with facial burns and hair coming off at the Parsons Green station in west London after the explosion on the train during the morning rush hour.
"At 8:20 this morning at Parsons Green station there was an explosion on a Tube train. We now assess that this was a detonation of an improvised explosive device," police counter-terror chief Mark Rowley said.
Rowley said most of the injuries were due to "flash burns", while others were wounded by the stampede as passengers ran out of the station in panic.
London Mayor Sadiq Khan said a "manhunt" was underway.
One local resident, Charlie Craven, who was on his way to the station, said he heard a "massive bang".
"I saw an orange sort of fireball encompassing the whole Tube coming towards you," he told AFP.
Witness Lauren Hubbard described it as "a wall of fire".
Twitter user @Rrigs, who posted pictures of a white bucket smouldering on the train, said: "Explosion on Parsons Green District Line train. Fireball flew down carriage and we just jumped out open door".
The bucket, which was inside a frozen food bag from the budget supermarket chain Lidl, looked like the type used by builders and there appeared to be cables coming out of it.
Police sources cited by British media said the device had a timer but had failed to detonate fully.
US President Donald Trump said that "loser terrorists" were behind the attack, adding that they were already "in the sights" of British police.
London's Metropolitan Police dismissed the tweet as "unhelpful speculation", and Trump was also rebuked by Prime Minister Theresa May.
"I never think it's helpful for anybody to speculate on what is an ongoing investigation," she said, speaking after an emergency cabinet meeting.
May also said the device was "clearly intended to cause significant harm," condemning it as a "cowardly attack".
Armed police on patrol
The National Health Service said 18 people were taken by ambulance to hospital, while four others made their own way to hospitals.
The London Ambulance Service said none of the victims "are thought to be in a serious or life-threatening condition".
The MI5 intelligence service is assisting investigators, and police said Londoners should expect additional security measures over the weekend.
Armed police and sniffer dogs could be seen on the train and around the station, which is in a leafy area of west London popular with well-off commuters, and filled with chic cafes.
The area around the station was later evacuated as bomb disposal experts secured what was left.
Local residents and businesses rallied together with businesses offering tea and the use of their toilets to people unable to get home.
The local council of Hammersmith and Fulham opened a rest centre in the area for those affected.
The bombing is the fifth terror attack in Britain since March, when a man mowed down pedestrians and stabbed a police officer outside the British parliament.
'Lots of screaming'
Passengers described chaotic scenes at the station in the normally quiet part of west London.
Louis Hather, 21, was travelling to work and was three carriages down from where the explosion took place.
"I could smell the burning. Like when you burn plastic," he told AFP.
Hather saw a woman with burns being carried away on a stretcher.
He was trampled on as passengers stampeded out of the station and his leg was badly cut and bruised.
Sally Faulding, a 51-year-old teacher, said: "People were falling over each other."
Richard Aylmer-Hall, 52, told the Press Association: "There was panic, lots of people shouting, screaming, lots of screaming".
A total of 35 people have been killed in four previous attacks in London and Manchester this year.
Three of those involved a vehicle ploughing into pedestrians.
The other attack was a bombing in May at a pop concert by US star Ariana Grande in Manchester which killed 22 people, including several children.
Otso Iho, a senior analyst at Jane's Terrorism and Insurgency Centre, said the latest attack showed a "continued high intent but low capability" of the terrorism threat in Britain.
Hans Michels, a professor of chemical engineering at Imperial College, said the flash flame "suggests that the explosion was only partly successful".
"Much of the bucket still seems to be intact and there appear to be no victims with lethal impact wounds," he said.
